The Simple Network Management Protocol (SNMP) provides facilities to manage and monitor network resources. SNMP consists of:
Agents—An agent is software that runs on a device that maintains information about device configuration and current state in a database.
Managers—An SNMP manager is an application that contacts an SNMP agent to query or modify the agent database.
The SNMP protocol—SNMP is the application-layer protocol SNMP agents and managers use to send and receive data.
Management Information Bases (MIB)—The MIB is a text file that specifies the managed objects by an object identifier (OID).
Important
The switch does not reply to SNMP requests sent to the Virtual Router Redundancy Protocol (VRRP) virtual interface address; it does, however, reply to SNMP requests sent to the physical IP address.
An SNMP manager and agent communicate through the SNMP protocol. A manager sends queries and an agent responds; however, an agent initiates traps. Several types of packets transmit between SNMP managers and agents:
Get request—This message requests the values of one or more objects.
Get next request—This message requests the value of the next object.
Set request—This message requests to modify the value of one or more objects.
Get response—An SNMP agent sends this message in response to a get request, get next request, or set request message.
Trap—SNMP trap is a notification triggered by events at the agent.